Discussion on the Application of Rapid Immunoblot Assay for AQP4-IgG Detection—Reply

Abstract

COMMENT & RESPONSEIn Reply We thank Su and Wang for their valuable insights of our recent article 1 on the rapid immunodot aquaporin 4 (AQP4) assay for neuromyelitis optica spectrum disorder (NMOSD).We perform strict quality control on the density of AQP4orthogonal arrays of particle structure (OAPs) and their concentration for each batch. Using the same procedure to extract AQP4-OAPs, the concentration of the active component in the resulting solution does not vary significantly. The membrane fraction solution is diluted in a 1.5-fold gradient to obtain 4 to 5 concentrations. Each solution is then spotted onto a nitrocellulose membrane to create test strips, with the same volume applied for each spot. The control group consists of test strips from the previous 1 to 2 batches. Staining was performed and compared using 1 to 2 long-term, preserved, positive serum controls. Finally, the solution with the same color development as the previous 1 to 2 batches of test strips was selected for test strip production. Also, another criterion is used to control this aspect. A long-term stored, strong, positive sample is diluted at a higher ratio (eg, 1:1000) and repeated 5 to 10 times, resulting in a weak positive signal. Then,